This invention relates to an apparatus and method for reading data. More particularly, the invention relates to the reading of white reference data in an apparatus capable of performing printing and document reading in selective fashion.
An ink-jet recording apparatus capable of being used as a scanner by detaching the printing head from a carrier and mounting instead a scanner head having substantially the same shape as that of the printing head so that documents can be optically read has not yet been proposed. The only similar example of such use available is a thermal transfer recording apparatus in which the ribbon cassette is replaced by a scanner cartridge.
In the case where a scanner head is mounted on the carrier in an ink-jet recording apparatus so that the apparatus may be used as a scanner, a white reference data is necessary as a reference for the amount of reading light required by the scanner head. The white reference data is required in order to compensate for individual differences among scanner heads and the ink-jet recorders with which they are combined, aging of the LED used as the light source for illuminating documents, a decline in quantity of light caused by environmental conditions, and differences from one light-receiving sensor to the next. It has been contemplated to obtain the white reference data by a white reference sheet utilizing the paper supply mechanism of the ink-jet recording apparatus. In order to prevent the white reference sheet from becoming soiled by the effects of printing error or ink mist at the time of printing, the white reference sheet is not installed in the printing space. Rather, the white reference sheet is supplied in the same manner as a document in the path traversed by the recording paper of the ink-jet recording apparatus or by the read document, then the carrier is moved to a predetermined position above the white reference sheet, the white reference sheet is read and the read value is adopted as the white reference of the read document. This method is advantageous in that error is small because when the white reference sheet is read, the position occupied by the reference sheet in the apparatus is the same as that of the actual document when the document is read.
With the above-described method, however, the user must make sure that the white reference sheet always traverses the same position. This is a troublesome operation.